1. Field of the Invention
The present invention relates generally to video conferencing, and more particularly to transmission of alternate image sources through a graphics side channel.
2. Description of Related Art
Videoconferencing systems provide a means for users at a local site to conference with users at a remote site by way of audio and video transmissions. These systems typically consist of a video source and an audio source that transmit images and sound from the local site for viewing and listening by the users at the remote site.
Due to bandwidth limitations, current videoconferencing systems can display either a conference camera image, typically showing the conference participants (i.e., the normal videoconference source), or a document camera image (e.g., an alternate video source), typically showing a computer screen display. They cannot, however, simultaneously display an alternate video source that can be displayed along with the normal videoconference source of the system.
Moreover, although some videoconferencing systems have the capability to preview an alternate video source, the user is forced to manually select whether the alternate video source should be transmitted as a live or still frame image. Even in systems where preview and send are automatic, the user is forced to view the live source in lower resolution than the still frame image. In all prior art systems, however, the normal conference video source is lost during the display of the alternate video source.
These prior art systems have several disadvantages. First, in many systems the user must manually select and send a live preview. Second, even if a live previewed image can be automatically transmitted, it is not transmitted in a high-resolution image format. Finally, the normal conference room video and the alternate video source cannot be viewed at the same time.
Based on the foregoing discussion, there currently exists a need to provide videoconferencing systems with the capability to display alternate video sources without the need for manual user intervention. There is also a need for the alternate video sources to have the capability to be displayed in a high-resolution format. Finally, there is a need to provide a system that will not sacrifice the loss of the normal conference video when the alternate video source is selected.